Excellent thermal stability of tavorite LixFeSO4F used as a cathode material for lithium ion batteries

Abstract

Tavorite LiFeSO₄F cathode material is prepared by the solvothermal method. The thermal stability of delithiated Li_xFeSO₄F is characterized by X-ray diffraction, differential scanning calorimetry and thermogravimetric analysis. It shows that the side reactions between the cathode material and the electrolyte are moderate, which involves the decomposition of Li_xFeSO₄F forming Fe₂(SO₄)₃ and Li₂SO₄ phases and F₂ gas. The onset temperature of the exothermal process is 358 °C with a minimal heat release of 79.4 J g⁻¹. The material undergoes further decomposition above 500 °C, which forms Fe₂O₃, Fe₃O₄ and Li₂O, associated with the release of SO₂ gas.